Emissions Estimate Builder

Every emissions figure is a sum of quantity × factor. This builds that sum in front of you. You supply both halves of every line — the activity quantity from your meters, invoices or weighbridge, and the emission factor from whichever published dataset or standard applies to your fuel, your region and your reporting year.

There are no factors inside this page. Enter yours, in kg CO₂e per unit of whatever the quantity is measured in, and keep the units consistent down each row.

The result is only as good as the factor you typed

This page performs arithmetic. It has no opinion about whether your factor is correct, and it cannot have one, because there is no such thing as the emission factor for a fuel or for a grid.

Factors differ by region, by fuel specification, by whether they cover carbon dioxide alone or all greenhouse gases converted to a carbon dioxide equivalent, by which global warming potential values that conversion used, by whether the figure is gross or net calorific basis, and by whether it includes emissions from producing and delivering the fuel or only from burning it. They are revised on a publication cycle, so last year’s number and this year’s number for the same fuel in the same country are routinely different. For electricity there is a further fork before any of that: a grid-average factor for where the load sits, or a supplier or contract-specific factor, which answer different questions and should both be computed.

A calculator that shipped with those numbers baked in would be quietly wrong somewhere, for someone, almost immediately — and the people least equipped to notice would be the ones who did not know a default had been applied. So the field is empty and it stays empty.

Record, next to your result, which dataset each factor came from and which edition. An estimate without that provenance is not reproducible, and an estimate nobody can reproduce is not auditable.

What each column is for

Description is yours to fill in — a meter, a supply point, a raw material stream. It appears in the breakdown line so the sum reads back as something you can check against source documents.

Kind separates combustion and energy emissions from process chemistry. Keeping them apart matters more in heavy industry than anywhere else: the two are derived by different methods, carry different uncertainties, and respond to completely different interventions. A fuel switch moves the first group and leaves the second untouched.

Activity quantity is whatever your factor is expressed per unit of — volume of gas, mass of coal, energy content, kilowatt hours, tonnes of raw meal, tonnes of clinker. The tool never sees the unit, so the only rule is that the quantity and the factor on a row must refer to the same one.

Factor is in kg CO₂e per unit of that quantity. If your source publishes in different units, convert before entering rather than hoping the arithmetic absorbs it.

Production quantity is optional, and produces an intensity figure: emissions per unit of output over the same period. Intensity and absolute emissions answer different questions and neither substitutes for the other — intensity tells you whether the process is improving, the absolute total tells you what was released.

Reading the shares

Each line’s share of the total is the reason to build the sum this way rather than in a single box. Abatement effort has to go where the mass is, and the distribution is frequently not where the site’s attention has been. A large share sitting on process chemistry means the fuel strategy, however good, has a ceiling built into it.

Two cautions on the shares. If the total is zero they are undefined and shown as a dash rather than as a misleading zero. And if you enter a negative factor to represent a captured or credited stream, the shares are computed against the net total, so they can exceed one hundred per cent or turn negative — which is arithmetically correct and visually confusing. Gross before net is the safer habit: total the sources first, and record any capture or credit separately rather than netting it into a line.

What this is not

It is not an inventory. A reporting inventory needs an organisational boundary, a consolidation convention, a scope classification for every source, a treatment for biogenic carbon, and documentation of what was measured versus estimated. This tool covers one step inside that process: turning activity data and factors into a total, transparently, with the working visible.

It is not a verification either. The self-test below checks that the arithmetic on this page matches a set of cases worked out by hand — nothing more. If it ever reports a failure, disregard the figures above it.

Nothing you type is transmitted or stored. The page makes no network requests of any kind; the computation happens in your browser and disappears when you close the tab.